Day: August 31, 2016

A sip-and-puff device is an assistive technology used by people who cannot use their hands. Being a quasi-medical device, you can imagine this technology is extremely expensive, incapable of being modified, and basically a black box that can’t do anything except what it was designed for. For his Hackaday Prize entry, [Jason] is building his own sip-and-puff interface that’s cheaper and more capable than the available commercial versions.

Sip-and-puff devices can be mapped to control a wheelchair, click a mouse, or press a key on a keyboard. You can do a lot with USB, so for this open sip-and-puff device, [Jason] is using the ever-popular ATmega32U4 microcontroller.

USB is only one part of the problem, and to measure the sips and puffs of air through a plastic hose, [Jason] is using a pressure sensor from Freescale/NXP. While this is very similar to what would be found in the off-the-shelf version of a sip-and-puff device, it’s rather hard to interface with. The current version of the board is using an instrument amplifier, and the mechanical connection between the pressure sensor and the board is slightly bizarre. [Jason] has a few ideas for a better sensor, and for the rest of the Hackaday Prize he’s going to work on redesigning this device with simplicity in mind.

Back in the days when you didn’t pay for your TV programming, it was common to have a yagi antenna on the roof. If you were lucky enough to have every TV station in the area in the same direction, you could just point the antenna and forget it. If you didn’t, you needed an antenna rotator. These days, rotators are more often found on communication antennas like ham radio beams. For terrestrial use, the antenna only needs to swing around and doesn’t need to change elevation. However, it does take a stout motor because wind loading can put a lot of force on the system.

[SP3TYF] has a HyGain AR-303 rotator and decided to build an Arduino-based controller for it. The finished product has an LCD and is able to drive a 24 V motor. You can control the azimuth of the antenna with a knob or via the computer.

Woodworking is the fine art of building jigs. Even though we have Internet-connected toasters, thermostats, cars, and coffee makers, the Internet of Things hasn’t really appeared in the woodshop quite yet. That’s changing, though, and [Ben Brandt]’s Internet of Things box joint jig shows off exactly what cheap computers with a connection to the Internet can do. He’s fully automated the process of making box joints, all with the help of a stepper motor and a Raspberry Pi.

[Ben]’s electronic box joint jig is heavily inspired by [Matthias Wandel]’s fantastic screw advance box joint jig. [Matthias]’ build, which has become one of the ‘must build’ jigs in the modern woodshop, uses wooden gears to advance the carriage and stock across the kerf of a saw blade. It works fantastically, but to use this manual version correctly, you need to do a bit of math before hand, and in the worst-case scenario, cut another gear on the bandsaw.

[Ben]’s electronic box joint jig doesn’t use gears to move a piece of stock along a threaded rod. Stepper motors are cheap, after all, and with a Raspberry Pi, a stepper motor driver, a couple of limit switches, and a few LEDs, [Ben] built an Internet-enabled box joint jig that’s able to create perfect joints.

The build uses a Raspberry Pi 3 and Windows IoT Core to serve up a web page where different box joint profiles are stored. By lining the workpiece up with the blade and pressing start, this electronic box joint jig automatically advances the carriage to the next required cut. All [Ben] needs to do is watch the red and green LEDs and push the sled back and forth.

In this three part video series we watch [Dirk Herrendoerfer] go from scraps to a nice 3D printed assembly as he iterates through the design of a pen plotter for making circuit boards.

[dana] mentioned [Dirk]’s work in the comments of this post which describes a different process. Many permanent markers stick to copper well enough to last through the chemical etching process. While hand drawing definitely produces some cool, organic-looking boards, for sharp lines and SMDs it gets a bit harder; to the point where it becomes advisable to just let a robot do it.

Of course, [Dirk] was aware of this fact of life. He just didn’t have a robot on hand. He did have some electronic detritus, fishing line, an Arduino, scrap wood, brass tubes, and determination. The first version‘s frame consisted of wooden blocks set on their ends with holes drilled to accept brass rods. The carriage was protoboard and hot glue. Slightly larger brass tubing served as bushings and guide. As primitive as it was the plotter performed admirably, albeit slowly.

The second version was a mechanical improvement over the first, but largely the same. The software got a nice improvement. It worked better and had some speed to it.

The latest version has some fancy software upgrades; such as acceleration. The frame has gone from random bits of shop trash to a nicely refined 3D printed assembly. Even the steppers have been changed to the popular 28BYJ-48 series. All the files, software and hardware, are available on GitHub. The three videos are viewable after the break. It’s a great example of what a good hacker can put together for practically no money.

[Seb Lee-Delisle]’s NES lightgun gave us pause as the effect is so cool we couldn’t quite figure out how he was doing it at first. When he pulls the trigger there erupts the beam of light Sci Fi has trained us to expect, then it explodes in a precision sunburst of laserlight at the other end as smoke gently trails from the end of the barrel. This is a masterpiece of hardware and trickery.

The gun itself is a gutted Nintendo accessory. It looks like gun’s added bits consist of two LED strips, a laser module (cleverly centered with two round heatsinks), a vape module from an e-cigarette, a tiny blower, and a Teensy. When he pulls the trigger a cascade happens: green light runs down the side using the LEDs and the vape module forms a cloud of smoke in a burst pushed by the motor. Finally the laser fires as the LEDs finish their travel, creating the illusion.

More impressively, a camera, computer, and 4W Laser are waiting and watching. When they see the gun fire they estimate its position and angle. Then they draw a laser sunburst on the wall where the laser hits. Very cool! [Seb] is well known for doing incredible things with high-powered lasers. He gave a fantastic talk on his work during the Hackaday Belgrade conference in April. Check that out after the break.

Accountants and MBAs use spreadsheets to play “what if” scenarios with business and financial data. Can you do the same thing with electronic circuits? The answer–perhaps not surprisingly–is yes.

Consider this simple common emitter amplifier (I modeled it in PartSim, if you’d like to open it):

In this particular case, there are several key design parameters. The beta of the transistor (current gain) is 220. The amplifier has an overall voltage gain of about 3 (30/10). I say about, because unless the transistor is ideal, it won’t be quite that. The supply voltage (Vcc) is 12 volts and I wanted the collector voltage (VC) to idle at 6V to allow the maximum possible positive and negative swing. I wanted the collector current (IC) to be 200mA.

We are all (hopefully) aware that we can be watched while we’re online. Our clicks are all trackable to some extent, whether it’s our country’s government or an advertiser. What isn’t as obvious, though, is that it’s just as easy to track our movements in real life. [Saulius] was able to prove this concept by using optical character recognition to track the license plate numbers of passing cars half a kilometer away.

To achieve such long distances (and still have clear and reliable data to work with) [Saulius] paired a 70-300 mm telephoto lens with a compact USB camera. All of the gear was set up on an overpass and the camera was aimed at cars coming around a corner of a highway. As soon as the cars enter the frame, the USB camera feeds the information to a laptop running openALPR which is able to process and record license plate data.

The build is pretty impressive, but [Saulius] notes that it isn’t the ideal setup for processing a large amount of information at once because of the demands made on the laptop. With this equipment, monitoring a parking lot would be a more feasible situation. Still, with even this level of capability available to anyone with the cash, imagine what someone could do with the resources of a national government. They might even have long distance laser night vision!